It is well known that the mining sector is one of hard work. Workers in the mining industry are subject to significant physical constraints. Indeed, some mining operations require that workers handle heavy tools that generate intense vibrations to accomplish their tasks manually.
For example, securing mining shaft ceilings or “vaults” requires the installation of anchors in the rock wall to support a wire mesh to prevent collapsing pieces of fractured rock falling on to workers. Indeed the nature of the soil as well as normal drilling and blasting cause the release of debris from the top vault of the mining tunnel. It is necessary to secure these ceiling arches by attaching a wire mesh that retains and prevents this rocky debris from falling over workers who travel in the mine shaft tunnels. To enable these lattices to retain large amounts of debris, and thus to be able to support heavy loads, to hang spacedly over the mine shaft ground level, the lattices must be fitted with efficient and elongated (e.g. 1.8 to 2.4 meters long) anchor rods. The process of fixing the mesh consists of drilling a hole of corresponding depth, then inserting capsules of epoxy resin, the insertion of the anchor rod which itself perforates the resin capsules, the mixing of the resin to start the reaction, to support the rod in place for curing the resin and finally the bolting of a support plate for holding the mesh to the projecting end of the rod. This still remains a delicate operation requiring human eye-hand coordination.
For several decades, workers used specialized tools such as jack legs and stopers designed for this kind of work and mine environments. In fact, these are the last remaining manual tools used in mining operations. They are still being used because of their particular qualities and benefits. Jack legs and stopers provide workers a power assist feed in their drilling operations. These tools may be used in a variety of ways with respect to spatial positioning, while taking only small spatial volume, they enable spatial positioning and a multi-directional orientation quickly and with few constraints. The positioning and orientation call upon human eye-hand coordination, and this goes without saying, this is a very efficient mechanism, quick and reliable. However, these tools are very heavy and generate higher vibration levels.
Along with other equipment, the jack leg is a tool weighing approximately 57 kilograms and which generates high levels of vibration. Thus, these mine workers sustain significant physical exertion during work and are exposed to very significant vibrations while working in a hazardous and often hostile environment. Therefore they are exposed to a high risk of injury as well as risk to develop certain occupational borne diseases associated, among others, to exposure to body vibrations.
Several studies and research in recent decades (e.g. Health and Safety Executive, UK) have established more clearly the detrimental effects to the human body when handling for a long time vibrating tools. Known in the medical literature under the name HAV (Hand Arm Vibration), a correlation is set between the level of vibration, duration of exposure and the likelihood of developing an occupational disease. The various types of hand drills (jack legs and stopers) in the mining industry generate vibration levels that far exceed the acceptable threshold. So the scientific community recognizes that prolonged exposure to high levels of vibration may have adverse effects on health, and more specifically: repetitive hand movements may be a factor of ischemia; unnatural hand positions (maladaptive grip, variable work posture and height) cause additional constraints and workloads which can lead to hardening of muscles and ligaments, which can cause injuries; tight grip (used with one hand, with vibrations, that we do not want to release) causes vascular and sensorimotor disorders; mechanical stress exerted on the palms of the hands (against handling blows, strike movements on components, working with a steel tool); vibrations; and Raynaud's syndrome (ischemia in the fingers, finger vasoconstriction induced by the nervous system). These factors are most incapacitating for workers with possible permanent physical damage. These factors in addition to increasing the specific health hazard of mine workers also have longer-term consequences.
A study by the Quebec Research Institute of Health and Safety at Work estimated at $CAN 4.64 billion the annual cost of occupational injuries, and $ CAN 40,180 annually per incapacitated worker the cost of an occupational disease whose origin comes from a repetitive work. According to the same study, the costs reach $ CAN 89,227 per year in the mining sector. This sector is thus at a high level of priority for the Health and Safety Board (CSST) to find ways to reduce these costs.